Well tonight – I finally got in the mental space to re-approach working on the MPU for the Dolly Parton pinball machine. I was disheartened when I finished the installation of the U8 last week.
I had verified all the connections were correct – and replaced the capacitor just below the IC. Everything then tested as I expected, so with great hope I put the board in the pin. My hopes were dashed when I powered the game on. Nothing happened other than a bit of beeoooop noise once. I flipped the power a couple of times – not expecting anything different, but hoping.
Dejected I took the board out, and placed it on my card table work bench.
So, a week later (today) I got the gumption up to work on the board again. I figured the reset section was not working correctly. The green LED comes on, but doesn’t go through the flicker/flash boot sequence. So somewhere something in that section must be out of whack. This is not coincidentally the same section that is usually directly affected by corrosion.
Today – I cut out and de-soldered everything else in this area. Imagine my surprise when I went to remove one of the larger resistors in this section the lead popped right off. Apparently there was more corrosion problems than I had assumed.
After sanding, scrubbing, cleaning I began to put in all the replacement parts that I had purchased last week for this section. I spent about three hours on this process I had one spot left for a resistor. I was annoyed after going through my entire box of parts and rechecking the bands on every loose resistor that I have.
I need to purchase one 20k ohm resistor to finish this project. Annoyed as I had gone with a list to the great local supplystore (ACK Electronics), and thought I’d purchased everything needed… but it appears I missed one item. I did get one resistor that didn’t match anything on my list – so it must be what’s wrong.
Guess I’ll be back to the store this week unless someone has one on hand they want to drop by. 😉
I had been hoping to see if this would bring the machine back to life – but it’ll be a bit longer until we find out.